TWI617599B - Thermoplastic resin shaped article and method for producing the same, thermoplastic resin light-guiding article, light source device and liquid crystal display device - Google Patents

Abstract

The present invention provides a thermoplastic resin molded body in which pores having excellent light-emitting efficiency are formed, and a thermoplastic resin light-guiding body using the same. The inside of the thermoplastic resin-molded material body is irradiated with a pulsed laser beam in a state of being focused, and a crack is formed inside the thermoplastic resin-molded material body, and then the thermoplastic resin constituting the thermoplastic resin-molded material body is formed. Heat treatment is performed at a temperature higher than the glass transition temperature to obtain a thermoplastic resin molded body 20 having only a substantially spherical pore 244 having a minimum diameter of 30 μm or more inside the surface of 10 μm or more.

Description

Thermoplastic resin molded body, method for producing the same, thermoplastic resin light guide, light source device, and liquid crystal display device

The present invention relates to a thermoplastic resin molded body, a method for producing the same, a thermoplastic resin light guide, a light source device, and a liquid crystal display device.

The liquid crystal display device is basically composed of a light source device and a liquid crystal display element. From the viewpoint of compacting the liquid crystal display device, a backlight (back light source device) of an edge light type is often used as the light source device. In the backlight of the edge illumination method, at least one side end surface of the rectangular plate-shaped light guide body is used as a light incident end surface, and a linear or rod-shaped primary light source such as a straight tube type fluorescent lamp or a light source is disposed along the light incident end surface. a point-like primary light source such as a light emitting diode (LED), such that light emitted from the primary light source is incident on the light incident end surface of the light guide body and introduced into the light guide body, and two light guide bodies are used. The light exit surface of one of the major surfaces emerges. The light emitted from the light exit surface of the light guide is diffused by a light diffusing element such as a light diffusing film disposed on the light emitting surface, by the cymbal The optical deflecting element such as a prism sheet is deflected in a desired direction. The light is also emitted from the main surface which is the main surface opposite to the light exit surface of the light guide, and a light reflection element such as a light reflection sheet is disposed so as to face the back surface in order to return the light to the light guide body.

The light guide body as described above can be formed by forming various optical functional structures in a thermoplastic resin molded body which is a material of a light guide. The optical functional structure includes, for example, a light emitting means for emitting light guided through the light guide body.

It has been disclosed that a bubble is used as the light-emitting means, and the bubble is formed by imparting radiation energy and heat energy (for example, see Patent Document 1).

[Previous Technical Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2006-155937

Along with the high definition of the liquid crystal display device or the low power consumption, it is required for the backlight to perform higher-luminance illumination with a primary light source having a smaller amount of light. Therefore, the light emitting means formed in the light guide body as the constituent member of the backlight is required to have a function of efficiently emitting light from the primary light source.

However, the light guide disclosed in Patent Document 1 uses bubbles formed at a predetermined density as the light-emitting means, but the bubble diameter is as small as 20 μm or less, specifically about 0.3 μm, so that the light emission efficiency of each bubble is low, and the brightness thereof is low. Not enough.

Further, in the method for producing a light guide of Patent Document 1, it is necessary to add a specific additive for inducing bubbles in order to form bubbles.

Further, in the method for producing a light guide of Patent Document 1, since bubbles are formed in a portion irradiated with the radiation energy, the radiation can be controlled in the irradiation surface of the radiation energy. The position at which the bubble is formed is difficult to control the position at which the bubble is formed in the depth direction parallel to the irradiation direction of the radiation energy.

An object of the present invention is to provide a thermoplastic resin molded body having pores having excellent light-emitting efficiency and a thermoplastic resin light-guiding body using the same, and a light source device and liquid crystal display using the thermoplastic resin light-guiding body. Device.

Another object of the present invention is to provide a method of producing a thermoplastic resin molded article having pores having excellent light-emitting efficiency without using an additive.

Another object of the present invention is to provide a method for producing a thermoplastic resin molded body which can form pores having excellent light emission efficiency at arbitrary positions inside the molded body.

The above problems are solved by the following inventions [1] to [13].

[1] A thermoplastic resin molded article having substantially spherical pores having a minimum diameter of 30 μm or more only inside the surface of 10 μm or more from the surface.

[2] The thermoplastic resin molded article according to [1], which has transparency.

[3] A thermoplastic resin molded body obtained by the following heat treatment step after the pulsed laser irradiation step shown below, and only in the heat of the heat The inside of the surface of the plastic resin molded body having a surface of 10 μm or more has substantially spherical pores having a minimum diameter of 30 μm or more;

(pulse laser irradiation step)

The inside of the surface of the thermoplastic resin molding material body is 10 μm or more, a step of irradiating a pulse laser in a state in which the pulse laser is in focus, and forming a crack only inside the thermoplastic resin forming material body;

(heating process step)

The thermoplastic resin molding material body in which the crack is formed is heat-treated at a temperature equal to or higher than the glass transition temperature of the thermoplastic resin constituting the thermoplastic resin molding material body, and is only 10 μm or more from the surface of the thermoplastic resin molding material body. The step of forming a substantially spherical void having a minimum diameter of 30 μm or more is formed inside.

The thermoplastic resin molded article according to any one of the aspects of the present invention, wherein the thermoplastic resin molded body of the thermoplastic resin molding raw material body has a decomposition-forming gas in the pores.

[5] A method for producing a thermoplastic resin molded body, which is a method for producing a thermoplastic resin molded body obtained by the following heat treatment step after the pulse wave laser irradiation step described below, and the heat is The plastic resin molded body has substantially spherical pores having a minimum diameter of 30 μm or more only inside the surface of the thermoplastic resin molded body of 10 μm or more;

(pulse laser irradiation step)

a step of irradiating a pulse laser in a state where the surface of the thermoplastic resin molding material body is 10 μm or more, in a state in which the pulse laser is in focus, and forming a crack only inside the thermoplastic resin molding material body;

(heating process step)

The thermoplastic resin molding material having cracks formed therein is formed at a temperature equal to or higher than the glass transition temperature of the thermoplastic resin constituting the thermoplastic resin molding material body. In the heat treatment, a substantially spherical pore having a minimum diameter of 30 μm or more is formed only inside the surface of the thermoplastic resin-molded material body by 10 μm or more.

[6] The method for producing a thermoplastic resin molded article according to the above aspect, wherein the pulse wave laser has a wavelength of 1080 nm or less, a pulse width of 200 femtosecond or less, and a pulse of 5 μJ/pulse or more. energy of.

[7] The method for producing a thermoplastic resin molded article according to the above [5], wherein the heat treatment time is 3 minutes or longer and 30 minutes or shorter.

The method for producing a thermoplastic resin molded article according to any one of the above aspects, wherein the temperature of the heat treatment is a glass transition temperature of the thermoplastic resin constituting the thermoplastic resin molded material body + 30 Above °C.

[9] A thermoplastic resin molded body according to any one of [1] to [4], which has a light incident end surface to which light introduced into the interior is incident, and The light exiting surface emitted by the light guided by the inside, and the haze value is 5% or less.

[10] A thermoplastic resin light guide comprising: a light incident end surface on which light introduced into the inside enters, and a light exit surface emitted from light guided inside, and having a haze value of 5% or less, and The thermoplastic resin light guide has substantially spherical pores having a minimum diameter of 30 μm or more only inside the light emitting surface of 10 μm or more.

[11] The thermoplastic resin light guide according to [9] or [10], which has a core-clad structure.

[12] A light source device comprising the primary light source of the thermoplastic resin light guide according to [9] or [10], wherein the primary light source is adjacent to the heat The light incident end surface of the plastic resin light guide is disposed.

[13] A light source device comprising the primary light source of the thermoplastic resin light guide according to [11], wherein the primary light source is disposed adjacent to the light incident end surface of the thermoplastic resin light guide.

[14] A liquid crystal display device comprising the light source device according to [12].

[15] A liquid crystal display device comprising the light source device according to [13].

According to the invention, it is possible to provide a thermoplastic resin molded body having pores having excellent light-emitting efficiency and a thermoplastic resin light-guiding body using the same.

Further, by using the thermoplastic resin light guide, it is possible to provide a light source device and a liquid crystal display device which emit light with high luminance.

Further, according to the present invention, it is possible to form a pore having a good light-emitting efficiency without an additive, and therefore, it is possible to provide a method for producing a thermoplastic resin molded article which is simple and can be reduced in cost.

Further, according to the method for producing a thermoplastic resin molded article of the present invention, pores having excellent light emission efficiency can be formed at any position inside the thermoplastic resin molded body, so that light from the primary light source can be efficiently emitted. A thermoplastic resin molded body.

The light source device using the thermoplastic resin light guide of the present invention is suitable, for example, for a monitor such as a personal computer, a backlight of a liquid crystal display device such as a liquid crystal display, or a ceiling light or the like. Light source used in lighting devices such as lighting and lighting billboards.

Further, the thermoplastic resin molded article of the present invention can be used, for example, as a monitor for a personal computer or the like, a diffusion plate for a liquid crystal display device such as a liquid crystal television, or a diffusion device for use in an illumination device such as an indoor illumination or a lighting billboard such as a cloud curtain lamp. Board, or design board for building materials, billboards, panels, etc.

1‧‧‧ femtosecond laser source

2‧‧‧Half-wavelength board

3‧‧‧Granley

4‧‧‧Shingles

5, 5', 5" ‧ ‧ mirror

6‧‧‧ Objective lens

7‧‧‧ femtosecond laser light

8‧‧‧ thermoplastic resin forming material body

9‧‧‧z axis platform

10‧‧‧Automatic twin-axis platform

20‧‧‧ thermoplastic resin molded body

22, 340‧‧‧LED

24, 600‧‧‧ thermoplastic resin light guide

26‧‧‧Light diffusing elements

28‧‧‧1st optical deflecting element

30‧‧‧2nd optical deflecting element

32‧‧‧Light reflecting elements

100‧‧‧ femtosecond laser processing equipment

101‧‧‧ Pulse laser irradiation area

241, 302‧‧‧light incident end face

242, 304‧‧‧ light exit surface

243, 303‧‧‧ back

244‧‧‧ holes

300‧‧‧Brightness measurement area

310‧‧‧reflector

320‧‧‧ mask

360‧‧‧Brightness meter

501‧‧‧ crack

700, 900‧‧‧ Formed with cracks

1301‧‧ ‧ core layer

1302‧‧‧Cladding

Fig. 1 is a schematic perspective view showing an embodiment of a thermoplastic resin molded body of the present invention.

Fig. 2 is a schematic view showing an embodiment of a femtosecond laser processing apparatus used for irradiation of a pulse laser.

Fig. 3 is a schematic cross-sectional view showing an embodiment of a thermoplastic resin light guide of the present invention.

Fig. 4 is a schematic cross-sectional view showing an embodiment of a light source device according to the present invention.

5(a) to 5(b) are schematic views showing an embodiment of a measuring device for normal brightness of a thermoplastic resin light guide.

Fig. 6 is a schematic view showing an embodiment of the arrangement of the pores of the thermoplastic resin light guide produced in the example.

Fig. 7 is a schematic view showing a sheet in which cracks are formed in the examples.

8(a) to 8(b) are schematic views of the thermoplastic resin light guide produced in the examples.

9(a) to 9(b) are schematic views of a sheet in which cracks are formed in the reference example.

FIG. 10 is a graph showing the relationship between the heat treatment time of the thermoplastic resin molded body at the temperature of various heat treatments in Reference Example 1 and the minimum diameter of the pores in the thermoplastic resin molded body.

FIG. 11 is a graph showing the relationship between the heat treatment time of the thermoplastic resin molded body at the temperature of various heat treatments in Reference Example 2 and the minimum diameter of the pores in the thermoplastic resin molded body.

FIG. 12 is an optical microscopic photograph showing an embodiment of the pore portion of the thermoplastic resin molded body produced in Reference Example 2. FIG.

Fig. 13 is a schematic perspective view showing an embodiment of a thermoplastic resin molded body of the present invention.

<The thermoplastic resin molded body>

The thermoplastic resin molded article according to the embodiment of the present invention has a substantially spherical pore having a minimum diameter of 30 μm or more only inside the surface of the thermoplastic resin molded body of 10 μm or more.

Examples of the thermoplastic resin constituting the thermoplastic resin molded body include an acrylic resin, a polycarbonate resin, a methacrylate-styrene copolymer (MS resin), and a cyclic olefin resin (Cyclo Olefin). Polymers, COP) and Acrylonitrile-Butadiene-Styrene (ABS) resin. When the thermoplastic resin molded article is used for optical applications, the thermoplastic resin is preferably an acrylic resin having high light transmittance in a wide wavelength range.

The thermoplastic resin molded body can be used in various shapes depending on the use of the thermoplastic resin molded body. The shape of the thermoplastic resin molded body in the case where the thermoplastic resin molded body is used as the light guide body is, for example, a plate shape.

In the thermoplastic resin molded body, those having transparency corresponding to the use can be used. For example, when a thermoplastic resin molded body is used as the light guide, the thermoplastic resin molded body preferably has a transparency of 5% or less.

<empty hole>

In the embodiment of the present invention, the void refers to a space existing inside the thermoplastic resin molded body or a thermoplastic resin light guide to be described later. For example, the crack generated by depolymerization or thermal decomposition of the thermoplastic resin constituting the thermoplastic resin molded body or the thermoplastic resin light guide can be expanded by heat to form voids. In this case, a decomposition gas of the thermoplastic resin exists in the pores.

The pores are present only inside the surface of the thermoplastic resin molded body or the thermoplastic resin light guide by 10 μm or more. The voids are present only within 10 μm or more from the surface of the thermoplastic resin molded body or the thermoplastic resin light guide, and the flicker of the light emitted from the light guide can be suppressed. The pores are preferably present only inside the surface of the thermoplastic resin molded body or the thermoplastic resin light guide by 20 μm or more, and more preferably only in the interior of 30 μm or more from the surface.

The minimum diameter of the pores is 30 μm or more. By setting the minimum diameter of the pores to 30 μm or more, the light-emitting efficiency when the thermoplastic resin molded body is used as the thermoplastic resin light guide can be improved. On the other hand, the minimum diameter of the pores is preferably 50 μm or more, and more preferably 70 μm or more. Inhibiting uneven brightness of light emitted from the light guide body In terms of the aspect, the maximum diameter of the pores is preferably 20 mm or less. When a thermoplastic resin molded body is used as a thermoplastic resin light guide that emphasizes optical transparency, the maximum diameter of the pores is preferably 1 mm or less, and the thermoplastic resin molded body is used as a design thermoplastic resin. In the case of a plate, the maximum diameter of the holes is preferably 20 mm or less.

Hereinafter, the minimum diameter of the hole will be described using FIG. Fig. 1 is a schematic perspective view showing an embodiment of a thermoplastic resin molded body of the present invention. When the thermoplastic resin molded body 20 is in the form of a plate, the thickness direction thereof is set to the z-axis direction, and the directions orthogonal to each other and orthogonal to each other are set to the x-axis direction and the y-axis direction. In the embodiment of the present invention, the minimum width of the hole 244 when the hole 244 is viewed from the z-axis direction and the y-axis direction is set to the minimum diameter, and the maximum width of the hole 244 is set to the maximum diameter. Further, the aspect ratio is a value obtained by dividing the maximum diameter by the minimum diameter.

The description of the minimum diameter and the aspect ratio described above is also applicable to the void existing in the interior of the thermoplastic resin light guide.

The shape of the void is substantially spherical. The so-called roughly spherical shape means that the shape is close to the ball and there is no angle. By setting the shape of the pores to be substantially spherical, the light-emitting efficiency when the thermoplastic resin molded body is used as the thermoplastic resin light guide can be improved. The aspect ratio of the holes is preferably 3 or less.

<The thermoplastic resin forming raw material body>

The thermoplastic resin molding raw material is a material used to obtain a thermoplastic resin molded body, and is a material at a stage before the formation of voids. The thermoplastic resin molded material body can be used in various shapes depending on the use of the thermoplastic resin molded body. For example, when a thermoplastic resin molded body is used as the light guide, the shape of the thermoplastic resin molded material body is, for example, a plate shape.

In the thermoplastic resin molded material body, those having transparency corresponding to the use can be used. For example, when the thermoplastic resin molded article is used as a light guide, the thermoplastic resin molded material preferably has a transparency of 5% or less.

<Method for Producing Thermoplastic Resin Molded Body>

The method for producing a thermoplastic resin molded body includes, for example, a method of producing a thermoplastic resin molded body by a heat treatment step after a pulse wave laser irradiation step, and the pulse wave laser irradiation step is performed on a thermoplastic resin molded material body. The inside of the surface of 10 μm or more is irradiated with a pulse laser in a state in which the pulse laser is in focus, and cracks are formed only in the thermoplastic resin molding material body; and the heat treatment step is to form a thermoplastic resin molding material body. The thermoplastic resin molded material body in which the crack is formed is heat-treated at a temperature equal to or higher than the glass transition temperature of the thermoplastic resin, and the minimum diameter is 30 μm or more only inside the surface of the thermoplastic resin molded material body of 10 μm or more. A generally spherical hollow.

(pulse laser irradiation step)

In the pulse laser irradiation step, the pulse laser is irradiated to the inside of the surface of the thermoplastic resin-molded material body by 10 μm or more in the state in which the pulse laser is in focus, thereby forming the raw material of the thermoplastic resin. A crack is formed at a target portion inside the body. The position of the focus of the pulse laser can be set to the thermoplasticity according to the purpose. Any position and depth inside the resin molded material body.

In order to form a crack only inside the surface of the thermoplastic resin-molded material body by 10 μm or more, it is preferable to use a pulse laser having a wavelength of a thermoplastic resin that transmits the thermoplastic resin-forming material body, and it is more preferable to use it. Multi-photon absorption pulse width laser pulse. By using a pulse laser having such a wavelength and a pulse width, the inside of the thermoplastic resin molded material body is irradiated in a state of being focused, and the irradiation energy can be concentrated at the target position. As a result, multiphoton absorption is generated, whereby the thermoplastic resin constituting the thermoplastic resin molding material body is depolymerized or thermally decomposed, and cracks can be formed at a target position inside the thermoplastic resin molding material body.

For example, when an acrylic resin is used as the thermoplastic resin constituting the thermoplastic resin molding material body, the pulse wave laser may have a pulse width of 20 nm or less at a wavelength of 350 nm to 1080 nm. For example, in the case of a pulse laser having a pulse width of 20 nm or less, pulse lasers having wavelengths of 355 nm, 525 nm, 780 nm, 790 nm, 808 nm, 830 nm, and 1064 nm can be cited. Further, for example, in the case of a pulse laser having a pulse width of 200 femtosecond or less, pulse lasers having wavelengths of 780 nm, 790 nm, 808 nm, and 830 nm are exemplified.

The size of the crack tends to increase as the output of the pulse laser increases, and the larger the number of the irradiation pulse, the larger the tendency. Therefore, the size of the crack can be adjusted by controlling the output of the pulse laser and the number of the pulse waves.

In order to cut the molecular bond of the thermoplastic resin molded material body, the pulse wave laser preferably has a pulse width of 200 femtosecond or less at a wavelength of 1080 nm or less, and It has an energy of 5 μJ/pulse or more.

The apparatus for irradiating the pulsed laser beam to the thermoplastic resin molded material body is, for example, a femtosecond laser processing apparatus 100 shown in Fig. 2 .

In FIG. 2, the femtosecond laser processing apparatus 100 is composed of a femtosecond laser light source 1, a half-wavelength plate 2, a Glan laser prism 3, a shutter 4, and a mirror. 5. A mirror 5', a mirror 5", an objective lens 6, a z-axis stage 9, and an automatic biaxial stage 10. The thermoplastic resin molding material body 8 as a workpiece is placed on the z-axis stage 9.

The femtosecond laser light 7 emitted by the femtosecond laser light source 1 passes through a half-wavelength plate 2, a Graham Ray 3, a shutter 4, a mirror 5, a mirror 5', a mirror 5", and an objective lens 6 in a focused state. Further, the thermoplastic resin is irradiated onto a predetermined portion of the inside of the thermoplastic resin molding material body 8. Further, the number of irradiation pulses of the femtosecond laser can be set by changing the laser irradiation time by the shutter 4. The adjustment of the focus position is performed by the z-axis platform 9 and the automatic biaxial platform 10.

(heating process step)

In the heat treatment step, the thermoplastic resin molded material body having cracks formed therein is heat-treated at a temperature equal to or higher than the glass transition temperature of the thermoplastic resin constituting the thermoplastic resin molded material body. Thereby, the crack grows into a void, and a thermoplastic resin molded body having only a substantially spherical pore having a minimum diameter of 30 μm or more inside can be obtained.

The size of the holes can be adjusted by controlling the size of the cracks. The hole has a tendency to become larger as the crack formed in the pulse laser irradiation step is larger.

The position of the pores in the thermoplastic resin molded body is substantially the same as the position of the crack formed in the thermoplastic resin molded material body, so that the position at which the pores are formed can be adjusted by the position at which the crack is formed. In the embodiment of the present invention, since the position at which the crack is formed in the thermoplastic resin molded material body is controlled by the focal position of the pulse laser, the pores can be formed at any position inside the thermoplastic resin molded body.

The temperature of the heat treatment of the thermoplastic resin molded material body is preferably equal to or higher than the glass transition temperature of the thermoplastic resin constituting the thermoplastic resin molded material body. By setting the temperature of the heat treatment of the thermoplastic resin molded material body to be equal to or higher than the glass transition temperature of the thermoplastic resin, the thermoplastic resin is softened, so that the pores can be grown in a short time. The temperature of the heat treatment of the thermoplastic resin molded material body is more preferably the glass transition temperature of the thermoplastic resin + 30 ° C or more, and further preferably the glass transition temperature of the thermoplastic resin + 50 ° C or more.

The higher the temperature of the heat treatment, the higher the growth rate of the pores tends to be, but the unevenness of the size of the grown pores tends to be large. On the other hand, the lower the temperature of the heat treatment, the more the growth rate of the pores tends to be slower, but the unevenness of the size of the grown pores tends to be small.

Further, the longer the heat treatment time, the more the pores tend to become larger, and the spherical shape having an aspect ratio of 1 close to the pores tends to be large. The heat treatment time is preferably 3 minutes or more in terms of reducing the unevenness of the pore size, and the heat treatment time is preferably 30 minutes or less in terms of improving productivity.

Examples of the method of the heat treatment include a method of heating by a heating furnace such as a hot air dryer, a method of heating by a hot wire such as an infrared heater, and the like. A method of heating in contact with a heat medium such as a high-temperature metal plate.

The portion where the heat treatment step is performed may be the entire thermoplastic resin molded material body or may be only a portion where voids are formed.

In the heat treatment step, in order to suppress deformation of the thermoplastic resin molded material body, for example, it is preferable to fix the resin material in a state in which the thermoplastic resin is molded, or to fix the outer peripheral portion of the raw material body by holding the thermoplastic resin. The heat treatment is performed in a state on the holder. In the embodiment of the present invention, an unnecessary portion of the obtained thermoplastic resin molded body may be trimmed after the heat treatment step as needed.

<Thermoplastic resin light guide>

The thermoplastic resin light guide of the embodiment of the present invention has a light incident end surface into which light introduced into the thermoplastic resin light guide is incident, and light emitted from the light guided inside the thermoplastic resin light guide. The exit surface has a haze value of 5% or less, and has a pore having a minimum diameter of 30 μm or more and a substantially spherical shape only inside the light emission surface of 10 μm or more. Further, in terms of transparency, the haze value of the thermoplastic resin light guide is preferably 5% or less. Further, a thermoplastic resin molded body can be used for the thermoplastic resin light guide.

Examples of the thermoplastic resin constituting the thermoplastic resin light guide include an acrylic resin, a polycarbonate resin, a methacrylate-styrene copolymer (MS resin), and a cyclic olefin resin (COP). Among these resins, an acrylic resin having high light transmittance in a wide wavelength range is preferable.

Plate-shaped thermoplastic for use in obtaining thermoplastic resin light guides For example, a molded article produced by a hot-melt process such as an injection molding method or an extrusion molding method, or an acrylic monomer as a raw material, using a propylene resin particle as a raw material, by a casting polymerization method Manufactured acrylic cast sheet.

Fig. 3 is a schematic cross-sectional view showing an embodiment of a thermoplastic resin light guide of the present invention.

The thermoplastic resin light guide 24 is set to a thickness direction in the vertical direction in FIG. 3, and is widened in a direction perpendicular to the paper surface, and has a rectangular plate shape as a whole. The thermoplastic resin light guide 24 has a light incident end surface 241. The light incident end surface 241 is a surface adjacent to the primary light source. At least one of the four side end faces of the thermoplastic resin light guide body 24 serves as a light incident end face 241. The thermoplastic resin light guide 24 has a light exit surface 242 as one main surface and a back surface 243 as a main surface on the opposite side. Further, in the present embodiment, only the upper surface is set as the light exit surface 242, but both surfaces may be set as the light exit surface 242. In the present embodiment, the thermoplastic resin light guide body having the smooth surface (mirror surface) of the light exit surface 242 is exemplified. However, the present invention is not limited thereto, and a lenticular lens or a lenticular lens can be formed on the light exit surface. Various shapes that give functions such as shape and microlens shape.

The thermoplastic resin light guide body 24 has a void 244 therein.

For example, a gas such as a decomposition-generating gas of a thermoplastic resin constituting the thermoplastic resin molding material body is contained in the pores 244, and the refractive index of the gas is greatly different from that of the thermoplastic resin constituting the thermoplastic resin molding material body. The hole 244 functions as a diffusing portion that transmits and reflects light. Thereby, at the light incident end The light incident on the surface 241 and guided by the inside of the thermoplastic resin light guide 24 is refracted, reflected or scattered in the holes 244, and a part is emitted from the light exit surface 242. Therefore, the void 244 functions as a light emitting means for emitting light guided through the inside of the thermoplastic resin light guide 24 from the light exit surface.

The plurality of holes 244 may be provided at any position inside the thermoplastic resin light guide body 24, and the number and arrangement pattern of the holes 244 may be appropriately adjusted to obtain desired optical performance. The arrangement pattern of the holes 244 is, for example, a random shape, a checkerboard pattern, and a most densely packed shape.

In addition, the voids 244 may be formed only in a partial region of the thermoplastic resin light guide 24, or may be formed in all regions.

In the thermoplastic resin light guide 24, an additional light emitting means can be formed on at least one of the light exit surface 242 and the back surface 243 of the light guide body 24 as needed. Examples of the additional light-emitting means include a micro uneven structure and a dot obtained by printing a light-scattering ink.

The thickness of the thermoplastic resin light guide 24 is, for example, 0.1 mm to 10 mm.

In addition to the plate shape of the uniform thickness as shown in FIG. 3, the thermoplastic resin light guide body 24 may have various cross-sectional shapes such as a wedge shape whose thickness is gradually reduced from the light incident end surface 241 toward the opposite end surface. The thermoplastic resin light guide can be obtained, for example, by using a thermoplastic resin molded material body produced by an injection molding method.

The color of the thermoplastic resin light guide 24 can be selected according to the purpose. For example, when the color of the primary light source is directly emitted, the thermoplastic resin is guided. From the viewpoint of light transmittance of the body, colorless transparency is preferred. Further, in the case of emitting a color different from the color of the primary light source, a colored person can be used.

As shown in FIG. 13, the thermoplastic resin molded body can be set as a multilayered plate-shaped body, if necessary. The thermoplastic resin molded body 20 of Fig. 13 has a cladding layer 1302 as a low refractive index resin layer, a core layer 1301 as a high refractive index resin layer, and a core of a three-layer structure as a cladding layer 1302 of a low refractive index resin layer. Layer-cladding structure. By setting this structure, it is possible to impart a characteristic that even if the surface of the thermoplastic resin molded body 20 is contaminated by dust or fingerprints, the contamination is not noticeable. The material of the core layer and the cladding layer is a combination of setting the core layer to an acrylic resin and setting the coating layer to polyvinylidene fluoride, or setting the core layer to a polycarbonate resin and coating the coating layer. Any combination of a refractive index of a material of a coating layer such as a combination of acrylic resins and a refractive index of a material of the core layer may be selected.

The thermoplastic resin light guide can be produced by the same method as the method of producing a thermoplastic resin molded body using a thermoplastic resin molded material.

<primary light source>

Examples of the primary light source used in the embodiment of the present invention include white light and colored light. The white light is exemplified by a white LED. The colored light is exemplified by a colored LED. Specific examples of the white LED include NSSW020BT (manufactured by Nichia Chemical Industry Co., Ltd., trade name). Specific examples of the colored LED include NESB064 (manufactured by Nichia Chemical Industry Co., Ltd., trade name).

<Light source device>

The light source device of the embodiment of the present invention is provided on the thermoplastic resin light guide body. A light source device for the primary light source is disposed adjacent to the light incident end surface of the thermoplastic resin light guide, and a primary light source is disposed.

A schematic cross-sectional view of an embodiment of a light source device of the present invention is shown in Fig. 4 .

In FIG. 4, the LED 22 is provided as a primary light source, and a plurality of LEDs 22 may be provided. In the case where a plurality of LEDs 22 are provided, the LEDs 22 may be arranged at a desired interval in a direction perpendicular to the plane of the paper of FIG. Further, in the case where a plurality of LEDs 22 are provided, it is preferable to arrange them in such a manner that the direction of the maximum intensity of the light emitted from each of the LEDs 22 is parallel.

The light diffusing element 26 is disposed on the light emitting surface 242 of the thermoplastic resin light guide 24. When the directivity of the light emitted from the light exit surface 242 has a desired exit angle and viewing angle, the light diffusing element 26 may be omitted. The light diffusing element 26 is exemplified by a light diffusing film.

The first optical deflecting element 28 is disposed on the light diffusing element 26, and the second optical deflecting element 30 is disposed on the first optical deflecting element 28. The first optical deflecting element 28 or the second optical deflecting element 30 may, for example, be a cymbal facing upward. The first optical deflecting element 28 and the second optical deflecting element 30 may be of the same type or of different types.

The ridgelines of the plurality of rows of the first light deflecting element 28 and the light exiting surface of the second light deflecting element 30 are orthogonal to each other. The ridge lines of the plurality of lines of the light-emitting surface of the first light deflecting element 28 are parallel to the light incident end surface 241, and the ridge lines of the plurality of lines of the light-emitting surface of the second light deflecting element 30 are perpendicular to the light incident end surface 241. Further, a plurality of ridge lines and a second light deflecting element 30 of the light-emitting surface of the first light deflecting element 28 may be provided. Both of the ridgelines of the plurality of columns of the light-emitting surface are inclined with respect to the light incident end surface 241 and are orthogonal to each other.

The thickness of the first optical deflecting element 28 and the second optical deflecting element 30 is, for example, 30 μm to 350 μm.

When the directivity of the light emitted from the light exit surface 242 has a desired exit angle and viewing angle, at least one of the first light deflecting element 28 and the second light deflecting element 30 may be omitted.

The light reflecting element 32 is disposed below the back surface 243. Examples of the light reflecting element 32 include a plastic sheet having a metal vapor deposition reflective layer on its surface, a white sheet containing a pigment, and a light reflection sheet such as a bubble sheet. Examples of the pigment include titanium oxide, barium sulfate, calcium carbonate, and magnesium carbonate. Further, when the amount of light emitted from the back surface 243 is as small as negligible, the light reflecting element 32 may be omitted.

In the light source device according to the embodiment of the present invention, the light reflection element similar to the light reflection element 32 may be disposed on the side end surface other than the light incident end surface 241 of the thermoplastic resin light guide 24 as needed.

<Liquid crystal display device>

A liquid crystal display device according to an embodiment of the present invention includes a light source device according to an embodiment of the present invention, and for example, a liquid crystal display device is disposed on the light source device of FIG.

[Examples]

The invention will now be described using the examples.

<Evaluation of voids and cracks>

An optical microscope (manufactured by Nikon Co., Ltd., trade name: Integrated Circuit (IC) inspection microscope ECLIPSE L200N) was formed in the same manner as in the case of the void shown in Fig. 1 in the formation of thermoplastic resin. The pores inside the body or thermoplastic resin light guide are observed from the z-axis direction and the y-axis direction. The minimum width of the hole when viewed from the z-axis direction and the y-axis direction is set to the minimum diameter, and the maximum width is set to the maximum diameter. Further, the value obtained by dividing the maximum diameter by the minimum diameter is taken as the aspect ratio. In addition, the minimum diameter and the aspect ratio mean the average value of the minimum diameter and the aspect ratio of the three cracks arbitrarily selected from the 16 cracks.

Further, the crack was also evaluated by the same method as in the case of the void.

<Measurement of normal brightness>

Using the light source device, the light emission efficiency of the holes was evaluated by the measurement of the normal brightness shown below.

By covering a region other than the luminance measurement region of the light exit surface of the light source device having the configuration shown in FIGS. 5( a ) to 5 ( b ) with a black mask, the LED 340 serving as the primary light source emits light at 20 mA. The normal brightness of the light emitted from the luminance measurement region 300 was measured using a luminance meter 360 (manufactured by Topcon Technohouse Co., Ltd., trade name: color luminance meter BM-7). In addition, the normal brightness is a relative value when the normal brightness in the case where the crack-formed sheet before the thermoplastic resin light guide is obtained is used instead of the thermoplastic resin light guide is set to 1.0.

(Production Example 1) Production of a femtosecond laser processing apparatus

Integra-C (trade name, wavelength: 790 nm, pulse width: 120 femtoseconds, pulse wave frequency: 1 kHz) manufactured by QUANTRONIX Co., Ltd. was used as the laser light. Source 1, a femtosecond laser processing apparatus 100 shown in Fig. 2 is produced.

(Example 1)

The acrylic resin pellet (manufactured by Mitsubishi Rayon Co., Ltd., trade name: Acrypet VH6 #001, mass average molecular weight: 86,000, glass transition temperature: 110 ° C) was used as a raw material to produce a thickness of 3 mm. Acrylic extruded tablets. Then, it was cut out from the obtained acrylic extruded sheet in a rectangular shape of 160 mm × 100 mm to obtain a thermoplastic resin molded material body.

Using the femtosecond laser processing apparatus 100, the focus of the pulse laser is aligned to a depth of 1.5 mm from the surface of the thermoplastic resin molded material body, and the laser output is 30 mW and the number of irradiation pulses is 2 pulses. The laser beam is irradiated downward to form a crack only inside the thermoplastic resin-forming material body. The irradiation operation of the pulse laser is further repeated 15 times while moving the automatic biaxial stage 10, and is in a region of 6 mm × 6 mm in the center of the main surface of the thermoplastic resin molded material body (the pulse laser irradiation region of Fig. 7). A crack having an arrangement pattern as shown in Fig. 6 is formed in 101), and the crack-formed sheet 700 shown in Fig. 7 is obtained.

The resulting crack-forming sheet 700 had the center of the crack at a depth of 1.5 mm from the main surface, the minimum diameter of the crack was 17 μm, and the aspect ratio of the crack was 10.7.

Then, the outer periphery of the sheet 700 on which the crack was formed was held by an aluminum holder, and a hot air dryer (manufactured by Satake Chemical Industry Co., Ltd., product name: hot air circulation high temperature dryer 41-S5) was used at 180 ° C. Heat treatment was performed for 6.5 minutes to grow cracks into voids, and a thermoplastic resin molded body having pores was obtained.

After the test piece for the thermoplastic resin light guide having the pulsed laser irradiation region 101 in the center of the main surface is cut out from the thermoplastic resin molded body having the void, the test piece is punched by a diamond bit. All of the side end faces were cut into a mirror surface, and a thermoplastic resin light guide 600 having a size of 30 mm × 100 mm as shown in Figs. 8(a) to 8(b) was produced.

The obtained thermoplastic resin molded body and the thermoplastic resin light guide had a center of a hole at a depth of 1.5 mm from the main surface, the smallest diameter of the hole was 85 μm, and the aspect ratio of the hole was 2.4.

As shown in Fig. 5 (a) to Fig. 5 (b), one LED 340 is disposed so as to face the light incident end surface 302 of the thermoplastic resin light guide 600 (Manufactured by Nichia Chemical Industry Co., Ltd., trade name: White LED NSSW020BT). The reflection sheet 310 is disposed on the back surface 303 opposite to the light exit surface 304 so as to face the back surface 303 (made by Teijin-Dupont Film Co., Ltd., trade name: Tetoron Film) UX, thickness 225 μm), to obtain a light source device. The normal brightness of the obtained light source device was measured. The normal brightness is 6.3.

In addition, the normal brightness is a relative value when the normal brightness of the crack-formed sheet obtained in Comparative Example 1 described later is set to 1.0.

The processing conditions of the pulse laser irradiation and heat treatment and the evaluation results of the obtained thermoplastic resin light guide are shown in Table 1.

(Example 2 to Example 4)

A thermoplastic resin light guide was obtained in the same manner as in Example 1 except that the processing conditions of the heat treatment were set to the conditions shown in Table 1. Directing thermoplastic resin The evaluation results of the bodies are shown in Table 1.

(Comparative Example 1)

A sheet in which cracks were formed was obtained in the same manner as in Example 1 except that the heat treatment was not performed. The evaluation results of the sheet in which the crack was formed are shown in Table 1.

(Examples 5 to 7)

A thermoplastic resin light guide was obtained in the same manner as in Example 1 except that the processing conditions of the pulse laser irradiation and the heat treatment were set to the conditions described in Table 2. The evaluation results of the thermoplastic resin light guide are shown in Table 2.

In addition, the normal brightness is a relative value when the normal brightness of the crack-formed sheet obtained in Comparative Example 2 described later is set to 1.0.

(Comparative Example 2)

A sheet in which cracks were formed was obtained in the same manner as in Example 5 except that the heat treatment was not performed. The evaluation results of the sheet in which the crack was formed are shown in Table 2.

(Reference example 1)

Acrylic resin particles (manufactured by Mitsubishi Rayon Co., Ltd., trade name: Acrypet VH6 #001, mass average molecular weight: 86,000, glass transition temperature: 110 ° C) were used as raw materials to produce a thickness of 3 mm. Acrylic extruded tablets. Then, it was cut out from the obtained acrylic extruded sheet in a rectangular shape of 160 mm × 100 mm to obtain a thermoplastic resin molded material body.

Using the femtosecond laser processing apparatus 100, the focus of the pulse laser is aligned to a depth of 1.5 mm from the surface of the thermoplastic resin molded material body, and the laser output is 30 mW and the number of irradiation pulses is 2 pulses. Next, the pulse laser is irradiated to form a crack only inside the thermoplastic resin molded material body. The irradiation operation of the pulse laser is further repeated three times while moving the automatic biaxial stage 10 to form a crack 501 having an arrangement pattern as shown in FIGS. 9(a) to 9(b), and is formed with A piece of crack 900.

Then, the outer periphery of the sheet 900 on which the crack was formed was sandwiched by an aluminum holder, and a hot air dryer (manufactured by Satake Chemical Industry Co., Ltd.) was used. The hot air circulation high-temperature dryer 41-S5) was heat-treated at the temperature and time shown in Table 3 to obtain a thermoplastic resin molded body. The processing conditions and the evaluation results of the obtained thermoplastic resin molded body are shown in Table 3.

In addition, the minimum diameter and the aspect ratio of the reference example are the average values of the minimum diameter and the aspect ratio of the four pores formed in the inside of the thermoplastic resin molded body.

The relationship between the time of the heat treatment at the temperature of each heat treatment and the minimum diameter of the pores is shown in Fig. 10 . Furthermore, the error bar in FIG. 10 indicates a non-uniform range of the minimum diameters of the four holes.

(Reference example 2)

A thermoplastic resin molded body was obtained in the same manner as in Reference Example 1 except that the processing conditions of the pulse laser irradiation and the heat treatment were set to the conditions described in Table 4. The evaluation results are shown in Table 4.

The relationship between the time of the heat treatment at the temperature of each heat treatment and the minimum diameter of the pores is shown in Fig. 11 . Furthermore, the error bars in Fig. 11 indicate the non-uniform range of the minimum diameters of the four holes.

As an example of the pores, an optical micrograph at the time of observing the pores obtained under the condition 27 from the z-axis direction and the y-axis direction is shown in FIG.

As is apparent from Tables 3 and 4, and Figs. 10 and 11, the manufacturing method according to the embodiment of the present invention can form voids in the inside of the thermoplastic resin molded body without using an additive. Further, it has been found that by controlling the processing conditions of the pulse laser irradiation and the heat treatment, voids having an arbitrary minimum diameter and an aspect ratio can be formed.

Further, as shown in Fig. 10 and Fig. 11, there is a tendency that the higher the heat treatment temperature, the shorter the time required to form the pores, but the larger the unevenness of the pore size. On the other hand, there is a tendency that the lower the heat treatment temperature, the longer the time required to form the pores, but the smaller the pore size is (i.e., the pores having the same size are easily formed).

(Reference Example 3)

The minimum diameter and the aspect ratio of the voids were determined in the same manner as in Reference Example 1 except that the processing conditions of the pulse laser irradiation and the heat treatment were set to the conditions described in Table 5. Among them, a muffle furnace (manufactured by Isuzu Seisakusho Co., Ltd., trade name: EPTS-11K) was used for the heat treatment. The evaluation results are shown in Table 5.

As is clear from Table 5, when heat treatment is performed at a heating temperature equal to or lower than the glass transition temperature of the thermoplastic resin constituting the thermoplastic resin molded body, voids having an aspect ratio of 3 or less can be formed.

Claims (14)

A thermoplastic resin molded body having a substantially spherical pore having a minimum diameter of 30 μm only inside a surface of 10 μm or more from a surface to be a light-emitting surface, and having thermoplasticity constituting a thermoplastic resin-forming raw material body in the above-mentioned pores The decomposition of the resin generates a gas. The thermoplastic resin molded article according to claim 1, which has a transparency of a haze value of 5% or less. A thermoplastic resin molded body obtained by the following heat treatment step after the pulse wave laser irradiation step shown below, and which is formed only from the thermoplastic resin molded body The surface of the light-emitting surface having a surface of 10 μm or more has a substantially spherical pore having a minimum diameter of 30 μm, and has a decomposition-forming gas of a thermoplastic resin constituting the thermoplastic resin-forming material body in the pore; (Pulse laser irradiation) Step) Irradiating the pulse laser in a state where the surface of the thermoplastic resin molded material body which is the light-emitting surface is 10 μm or more, in a state in which the pulse laser is in focus, and the thermoplastic resin-forming material body is formed only a step of forming a crack in the inside; (heating step) heat-treating the thermoplastic resin molding material body in which the crack is formed at a temperature equal to or higher than a glass transition temperature of the thermoplastic resin constituting the thermoplastic resin molding material body. Only within 10 μm or more of the surface of the thermoplastic resin molded material body to be the light-emitting surface Minimum diameter of 30μm is formed approximately The step of a spherical void. A method for producing a thermoplastic resin molded body, which is a method for producing a thermoplastic resin molded body obtained by a heat treatment step described below after a pulse wave laser irradiation step shown below, and wherein the thermoplastic resin is formed The body has a substantially spherical pore having a minimum diameter of 30 μm inside the surface of the thermoplastic resin molded body which is 10 μm or more from the surface on which the light-emitting surface is formed, and has thermoplasticity constituting the thermoplastic resin-forming raw material body in the pore. (Decomposition of the resin to generate a gas; (pulse-wave laser irradiation step) irradiates the pulse wave in a state where the surface of the thermoplastic resin molded material body is 10 μm or more which is the surface of the light-emitting surface, and the focus of the pulse laser is aligned. The step of forming a crack only in the inside of the thermoplastic resin molded material body; (heating step) forming a crack at a temperature higher than a glass transition temperature of the thermoplastic resin constituting the thermoplastic resin molded material body The above thermoplastic resin molding material body is subjected to heat treatment only from the above thermoplastic resin A step of forming a substantially spherical pore having a minimum diameter of 30 μm in the inside of the surface of the molded material body which is a surface of the light-emitting surface of 10 μm or more. The method for producing a thermoplastic resin molded article according to claim 4, wherein the pulse wave laser has a wavelength of 1080 nm or less, a pulse width of 200 femtosecond or less, and an energy of 5 μJ/pulse or more. Forming thermoplastic resin as described in claim 4 or 5 In the method for producing a body, the heat treatment time is 3 minutes or longer and 30 minutes or shorter. The method for producing a thermoplastic resin molded article according to the fourth aspect of the invention, wherein the temperature of the heat treatment is a glass transition temperature of the thermoplastic resin constituting the thermoplastic resin molding material body + 30 ° C or higher. A thermoplastic resin molded body using the thermoplastic resin molded body according to the first aspect of the invention, which has an incident end surface of light incident on the inside and a light guided inside. The light exit surface has a haze value of 5% or less. A thermoplastic resin light guide having a light incident end surface on which light introduced into the inside and a light exit surface emitted from light guided inside, and having a haze value of 5% or less, and the above thermoplasticity The resin light guide body has a substantially spherical pore having a minimum diameter of 30 μm in a distance of 10 μm or more from the surface on which the light exit surface is formed, and has a decomposition of the thermoplastic resin constituting the thermoplastic resin molded material body in the pore. Generate gas. The thermoplastic resin light guide body according to claim 8 or 9, which has a core layer-clad layer structure. A light source device comprising a primary light source on a thermoplastic resin light guide according to claim 8 or 9, wherein the primary light source is adjacent to the thermoplastic resin light guide. The light is incident on the end surface. A light source device is the heat as described in claim 10 The plastic resin light guide body is provided with a light source device of a primary light source, and the primary light source is disposed adjacent to the light incident end surface of the thermoplastic resin light guide. A liquid crystal display device comprising the light source device according to claim 11 of the patent application. A liquid crystal display device comprising the light source device according to claim 12 of the patent application.